This invention is directed to compressors, and more particularly, to a system and method for reducing pressure pulsation in compressors, and particularly screw compressors, through liquid injection into the compression cycle for reducing radiated noise.
Conventional air conditioning systems cool air or other media by using four main components, including a compressor, condenser, metering device, and an evaporator. These components also provide the basis for most refrigeration cycles. Generally, the compressor compresses refrigerant gas to a high pressure, high temperature, superheated gaseous state for use by the condenser. The condenser, in cooling the superheated gas by rejecting heat to another cooler external medium, produces a sub-cooled liquid refrigerant with a high pressure and lower temperature. The metering device, such as an expansion valve, produces a low temperature, low pressure saturated liquid-vapor mixture from the sub-cooled liquid. Finally, the evaporator, by absorbing heat from the medium to be cooled, converts the saturated liquid-vapor mixture, to a low temperature, low pressure superheated gas for use by the compressor. The overall performance and efficiency of refrigeration cycles are directly dependent upon the heat transfer provided by the condenser and evaporator and is further dependent upon the performance and lubrication of the compressor.
Beyond performance, an additional and significant consideration in designing refrigeration cycles for systems such as a chiller systems is noise production. Based on the typical proximity of such systems and equipment to people, noise reduction is a major concern and design parameter. As the heart of the refrigeration system, compressors typically are responsible for the generation of the most noise of the system components described herein. That is, during the compression process, dynamic pressure pulsations develop within the compressor, particularly at the discharge port. Dynamic pressure pulsations, particularly at the discharge port, are commonly the direct result of unsteady mass flux that occurs during the compression process and are a large contributor to radiated noise in such systems.
While various methods and systems have been tried to reduce this noise associated with pressure pulsations, thus far many of these have proven ineffective in significantly reducing radiated noise generated in the compression process.
There exists a need, therefore, for an improved compressor design and method for reducing radiated noise in compressors which develops through the compression cycle due to pressure pulsations.
The primary object of this invention is to provide an improved system and method for reducing radiated noise which is produced in compressors during the compression cycle due to mass flux and pressure pulsations.
Another object of this invention is to provide an improved system and method for reducing radiated noise in compressors through liquid injection into the compression cycle.
Still another object of this invention is to provide an improved system and method for reducing radiated noise in compressors through liquid injection into the compression cycle at or near the discharge port.
The foregoing objects and advantages presented in the Best Mode are achieved by the compressor of the present invention for compressing refrigerant in an air conditioning or refrigeration system. The compressor includes a housing having a suction port, a discharge port, and a compression chamber, a mechanism for producing a compression cycle for compressing the refrigerant, wherein the compression cycle occurs in the suction port, discharge port and compression chamber, and a mechanism for providing liquid refrigerant into the compression cycle at a desired location for reducing pressure pulsations and associated radiated noise produced during the compression cycle.